If your students are writing in Google Docs and sharing all their documents with you, your Google Drive is going to be inundated with documents. The best advice I can offer is to have your students create a writing folder in their Google Drive, label it writing, and have them share the folder with you. You can make a class writing folder in your Google Drive and drag all your students' folders into your folder. As long as your students are writing documents in their writing folders they will automatically be shared with you.
When it is time to correct all those documents and you find yourself constantly typing the same comment over and over, there are a few things you can do to save yourself some time. The shortcut for inserting a comment in a Google Doc is cmd+option+m, it may only save a few seconds at a time but they will add up. Another time- saver would be to create a document with frequently used comments, then you could copy and paste, (cmd +c (copy) cmd+v (paste)), your comments instead of continually typing the same thing again and again. Below is a video from Caitlyn Tucker that will show how to add "shortcuts" that you can create in preferences under your tools tab in Google Docs.
I hope these were helpful.